The present invention relates to both a cassette for containing a sheet article such as a stimulable phosphor sheet or an X-ray film and a sheet article containing system for containing the sheet article in a container such as the cassette. More particularly, the present invention relates to both a cassette having a holding function to contain the sheet article,even if it is in a vertical position with its ejections lot down, or to eject the sheet article and a sheet article containing system having a holding function to contain the sheet article, even if the cassette is in the vertical position with its ejection slot down, and/or a function to eject the sheet article.
As is well known in the art, a fluorescent material (phosphor) of some kind stores a portion of the radiation energy of a radiation (e.g., X-ray, .alpha.-ray, .beta.-ray, .gamma.-ray, electron beam or ultraviolet ray), when irradiated, and exhibits the extinct luminescence (stimulated emission) according to the stored energy if it irradiated with an excited ray (stimulating ray) such as a visible light. The fluorescent material having such characteristics is called the stimulable phosphor substance (or the luminescence-extinct fluorescent substance).
The assignee previously has proposed a radiation image information recording/reproducing system (as disclosed in the U.S. Pat. No. 4,258,264), in which the radiation image information of an object such as a human body are once recorded in a sheet having a layer of stimulable phosphor material (which will be shortly referred to as the "fluorescent sheet" or "phosphor sheet") by making use of the stimulable phosphor material and in which the radiation image of the object is outputted as a visible image to a recording material such as a photosensitive material or a display such as a CRT on the basis of image signals by scanning the phosphor sheet two-dimensionally with an excited beam such as a laser beam to establish a luminescence-extinct light, and by reading this luminescence-extinct light photoelectrically to produce those image signals.
In this radiation image information recording and reproducing system, the operations of recording and reading the image on and from the phosphor sheet are accomplished in the prior art in the following manners.
First of all, the storage and recording of the radiation image information in the phosphor sheet are accomplished by containing the phosphor sheet in a shielding container called the "cassette" and by irradiating the sheet with the radiation through the object or by holding the sheet in contact with the object containing a radiation marker substance. The phosphor sheet recorded with the image is loaded, while being contained in the cassette, in the radiation image information reading apparatus (which will be shortly referred to as the "reading apparatus"). When this reading apparatus is loaded with the cassette, the phosphor sheet is ejected from the cassette by the sheeting mechanism of the reading apparatus and is conveyed to the image reading unit. In this image reading unit, an excited optical beam having a constant intensity emitted from an excited beam source such as a He--Ne laser is reflected and deflected in a main scanning direction by an optical deflector such as a galvanometer mirror to irradiate the phosphor sheet through various optical elements such as an f.theta. lens. Here, the phosphor sheet is conveyed in an auxiliary scanning direction substantially perpendicular to the main scanning direction by conveyer means such as a belt conveyor or nip rollers. As a result, the excited beam thus deflected in the main scanning direction can scan the phosphor sheet two-dimensionally all over its surface. From the portion of the phosphor sheet irradiated with the excited beam, there is generated the luminescence-extinct light according to the radiation image information which is stored in that portion.
This luminescence-extinct beam is either directly incident upon the incidence face of the optical guide or reflected by a condensing mirror, which is arranged to face that incidence face, to come into the incidence plane of the optical guide. The beam is then guided by the optical guide into a photomultiplier through a filter for cutting the light in the wavelength range of the excited beam so that it is photoelectrically converted into electric signals. These electric signals are processed so that they are reproduced as the visible image on the CRT or the photosensitive material or recorded and stored in the various recording mediums.
Thus, in the radiation image information recording and reproducing system, the phosphor sheet is basically handled while being contained in a shielding casing called the cassette. This is because the phosphor sheet will have its stored and recorded image information erased, if irradiated with a light, or will be stored and recorded as the image information with the ultraviolet ray contained in the light. Therefore, the phosphor sheet may preferably be handled as shielded as possible. For this preference, the ordinary reading apparatus is loaded with the phosphor sheet stored and recorded with the image information, while being contained in the cassette, as has been described hereinbefore, and the image information is read out by ejecting the phosphor sheet from the cassette in the apparatus. On the other hand, the stimulable phosphor sheet having been read is contained again in the cassette after its residual radiation image information has been erased.
Here, the cassette for containing the phosphor sheet is ordinarily constructed of a casing and a cover for the casing such that it can be opened and closed by supporting one side of the cover on the casing. In the conventional reading apparatus using such cassette and phosphor sheet, when the cassette containing the phosphor sheet is set in a predetermined position, the cover is opened by opening means using the complicated link mechanism or by sucking means such as a suction cup to stick the cover. Then, the phosphor sheet is ejected to the outside of the cassette (or the casing) by sheeting mechanism using the sucking means and is placed on the predetermined position of conveyer means and conveyed to the reading position by the conveyer means including paired rollers, a belt conveyor and guide members. Moreover, the phosphor sheet having been read is contained again in the cassette after its residual radiation image information has been erased, as has been described hereinbefore, so that it may be prepared for a subsequent image recording operation (as disclosed in the U.S. Pat. Nos. 4,777,365 and 5,061,852).
Specifically, the conventional reading apparatus has to be equipped, so as to eject the phosphor sheet from the cassette and to contain it again, with the complicated cassette opening mechanism using the link mechanism or the sucking means, the complicated sheeting mechanism for the phosphor sheet using the sucking means, and the control unit for these operation so that it is complicated and large-sized to raise its production cost.
In view of these problems, on the other hand, the assignee has proposed a reading apparatus and a sheet ejecting mechanism, in which the cassette is loaded generally in a vertical position with its opening (i.e., an ejection slot or an insertion slot) and in which the phosphor sheet is caused to fall by its empty weight by opening the cassette by means of a wedge or solenoid, as disclosed in the U.S. Pat. No. 4,889,989. According to these proposals, the apparatus can be simplified because it need not use the complicated link mechanism or the sucking means as the opening mechanism or the sheeting mechanism.
Incidentally, since the reading apparatus (or mechanism) using the fall due to the empty weight is loaded with the cassette having its open end down, the phosphor sheet having been read is seriously hard to be contain as it is in the cassette. Thus, the cassette has to be moved to another place so as to have its open end directed upward, or the phosphor sheet having been read has to be contained in the cassette manually by the operator.